1. Field of the Invention
The present invention generally relates to electronic apparatuses and, more particularly, to a plug-in unit and a housing of an electronic apparatus, which performs information processing or communication using optical modules.
2. Description of the Related Art
Among electronic apparatuses of optical communication systems that multiplex optical signals, there is one in which an optical cable is connected to a plurality of printed wiring board through optical connectors so as to perform information processing or optical communication (for example, refer to Japanese Laid-Open Patent Application No. 2000-147269).
There is a demand for such an electronic apparatus to increase a capacity of a trunk network due to an increase in an amount of information to be transmitted and an increase in a demand of data transmission in association with popularization of the Internet. In order to satisfy such a demand, an increase in an information transmission capacity and an improvement of functions are required for such an electronic apparatus. However, the optical connector mentioned above cannot handle a wide variety of signals, and, thus, an electronic apparatus using optical modules is used.
Recently, an SFP module, which is one of optical modules, has become popular, and an attachment case and a connector for attaching the SFP module are mounted to many plug-in units. Thus, in many cases, the SFP module is mounted to the plug-in unit with an optical cable connected to the attachment case. Such an SFP module is configured and arranged to permit an addition of modules or a replacement with other modules.
Such an electronic apparatus is connected with circuits corresponding to necessary number of lines initially so as to minimize an initial installation cost required for the electronic apparatus. Then, an addition or replacement of optical modules or electric modules may be performed if necessary.
FIG. 1 is a perspective view of a conventional electronic apparatus. FIG. 2 is a plan view of a plug-in unit to which a back board is attached. FIG. 3 is a plan view of the electronic apparatus accommodate in a locker. It should be noted that “front side” shown in FIGS. 1 through 3 indicates a side of the electronic apparatus 10 where attachment levers 14 are provided, and “apparatus back side” indicates a side of the electronic apparatus 10 opposite to the side where the attachment levers 14 are provided.
As shown in FIG. 1 through 3, the electronic apparatus 10 generally comprises a housing 11, a plurality of plug-in units 12 and a back board 25. As shown in FIG. 1, an opening is formed in the housing 11 on the front side so that the plug-in units 12 are inserted and into the housing 11 through the opening and are accommodated in the housing 11.
The plug-in unit 12 comprises a printed wiring board 13, the attachment levers 14, attachment cases 15, electronic parts 16, LED parts 17, optical modules 18, plugs 19, optical cables 21 and connectors 23 for electric connection. The electronic parts are mounted on the printed wiring board 13.
The attachment levers 14 for attaching the plug-in unit 12, the attachment cases 15 for attaching the optical modules 18 and LED parts 17 for indicating operations are provided on the front side of the printed wiring board 13. Additionally, indication labels are provided in the vicinity of the respective LED parts 17.
A connector 22 to be connected to the optical module 18 is provided in each of the attachment cases 15. As shown in FIG. 2, the optical cables 21 are connected to the printed wiring board 13 by attaching the optical modules 18 to the attachment cases 15. The optical modules 18 are not always connected to all the attachment cases 15, and only a desired number of optical modules 18 are connected to the respective attachment cases 15. Additionally, the optical cables 21 are bundled by holders 24 so that the LED parts 17 and the indication labels can be checked easily. The connectors 23 for electric connections are mounted on the printed wiring board 13 on the back side so as to connect the back board 15 to the printed wiring board 13.
The back board 25 comprises a back board body 26 and plugs 27 mounted on the back board body 26. The back board 25 is electrically connected to the plug-in unit 12 by attaching the plugs 27 to the connectors 23.
The electronic apparatus 10 is accommodated in a locker 29 as shown in FIG. 3, and is supported by support parts 29a. An area A is provided between a front face 29A and the electronic apparatus 10 so that the bundled optical cables 21 are accommodated therein. Additionally, reinforcing members 31 are provided to the support parts 29a of the locker 29 so as to firmly support the electronic apparatus 10.
According to the electronic apparatus 10 having the above-mentioned structure, a necessary number of optical modules 18 can be mounted so as to minimize the initial investment to the electronic apparatus 10. Additional optical modules 18 can be attached without removing the plug-in unit 12 while other lines are being in operation. The optical modules 18 can be replaced with other kinds of modules having a different transmissible distance.
However, there is a problem in the conventional electronic apparatus 10 in that a number of optical modules 18 for attaching the optical modules 18 is limited due to a limited area where the attachment cases 15 are provided since the attachment cases 15 are mounted to the printed wiring board 13 on the front side where the LED parts 17 and the indication labels are provided.
Additionally, there is a problem in that the optical cables are obstructive when inserting or removing the plug-in unit 12 since the optical modules connected to the optical cables 21 are attached to the attachment cases 15 provided on the front side of the apparatus. Further, there is a problem that it is difficult to visually recognize the LED parts 17 and the indication labels since the optical cables form an obstacle. Furthermore, the optical cables 21 connected to the plug-in unit 12, which is to be removed from the housing 11 for maintenance check, must be removed from the plug-in unit 21 concerned, which deteriorates maintainability.
Additionally, there is a problem in that the reinforcing members 31 must be provided to the support parts 29a of the locker 29 since the area A, where the bundled optical cables 21 are accommodated when the electronic apparatus 10 is accommodated in the locker 29, must be provided on the side of the front face 29A of the locker 29.